The proposed research is to elucidate the nature of gonadotropic hormone effect on embryonic ovary during development. Studies have been designed to investigate the steroid hormone secretion from the left and right ovaries during various developmental stages and in response to gonadotropic hormone effect. The types and amount of steroid hormone secreted into the culture medium and present in the tissue will be measured by radioimmunoassay. The appearance of gonadotropic hormone receptors, adenylate cyclase system and guanylate cyclase system in the embryonic ovary will be assessed. The gonadotropic hormone receptors which reside in the ovarian plasma membrane will be detected by their ability to bind iodinated hormone. Adenylate cyclase, or guanylate cyclase activity and cyclic AMP or cyclic GMP phosphodiesterase activity present in the embryonic ovary and their changes due to gonadotropic hormone stimulation will be measured by their ability to convert ATP or GTP to cyclic AMP or cyclic GMP and the destruction of cyclic AMP or cyclic GMP respectively. The amount of the cyclic AMP remains in the tissue and its releases into the culture medium during gonadotropic hormone stimulation will be measured by competition protein binding assay and the cyclic GMP level in the tissue or medium will be measured by radioimmunoassay. Biochemical parameter measured during the various developmental stages will be correlated to the morphological changes of the left and right ovaries throught light and electron microscopic examination. Hormone-involved chromosomal protein modification will be investigated by labeling the chromatin acidic protein and histone with P32 and C14 acetate, and the changes in chromatin template activity will be measured by the rate of RNA synthesis in vitro. The findings will serve as a key toward the understanding of gonadotropic hormone involved reproductive system development.